Nucleic acid extraction protocols can be broadly classified into silica based and non-silica based protocols. The existing silica and non-silica protocols cannot tolerate a water wash to remove non-nucleic acid components and require an aqueous wash with some percentage of alcohol in it. Presence of alcohol in eluted nucleic acid solution inhibits polymerase chain reaction (PCR) and hence, typically both the protocols require a high speed spinning or other methods to remove residual alcohol and elution of nucleic acids with a room temperature or elevated temperature aqueous buffer. In some cases, both the protocols require a high salt concentration with polyethylene glycol or an aqueous alcohol wash. The use of high concentration of salts and aqueous alcohol puts a restriction on the elution of nucleic acids like strict removal of these components before nucleic acids are eluted or use of centrifuge etc. Hence, none of the existing silica or non-silica based protocols can be used at point of care (POC) as a centrifuge will generate aerosols. Some of the non-silica based protocols reported in literature are given below:
U.S. Pat. No. 7,264,927: This document describes use of cellulose or cellulose paper involving use of polyalkylene glycol and high salt concentrations to bind and finally, elute the nucleic acids in a buffer or deionized water.
U.S. Pat. No. 6,084,091: Describes method of using cellulose flour (like potato starch) for nucleic acid isolation.
U.S. Pat. No. 5,804,684: Describes a method to use filter paper for nucleic acid extraction, where it is housed in a material like a plastic tip with the help of a soft tissue paper or piece of cotton as filter or barrier to support the filter paper.
All the above processes use either commercially available silica columns for final nucleic acid isolation, or require longer sample processing times (greater than 30 mins) or involve use of high concentrations of salts during washing of matrix or use of centrifuges etc. None of the cellulose based nucleic acid extraction methods wash the nucleic acids with a 100% aqueous buffer or water and usually containing a percentage of alcohols or polyol containing compounds.